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In order to obtain a lightweight, high-strength, and customizable cellular structure to meet the needs of modern production and life, the mechanical properties of four thickness gradient honeycomb structures were studied. In this paper, four types of honeycomb structure specimens with the same porosity and different Poisson's ratios were designed and manufactured by using SLA 3D-printing technology, including the honeycomb, square honeycomb, quasi-square honeycomb, and re-entrant honeycomb structures. Based on the plane compression mechanical properties and failure mode analysis of these specimens, the thickness gradient is applied to the honeycomb structure, and four structural forms of the thickness gradient honeycomb structure are formed. The experimental results show that the thickness gradient honeycomb structure exhibits better mechanical properties than the honeycomb structure with a uniform cellular wall thickness. In the studied thickness gradient honeycomb structure, the mechanical properties of the whole structure can be significantly improved by increasing the thickness of cell walls at the upper and lower ends of the structure. The wall thickness, arrangement order, shape, and Poisson's ratio of the cell all have a significant impact on the mechanical properties of the specimens. These results provide an effective basis for the design and application of cellular structures in the future. [ABSTRACT FROM AUTHOR]

The article discusess a study conducted for analysing utility of totally implantable venous access ports in patients with breast cancer. The study showed that totally implantable venous access port implantation through internal jugular vein or subclavian puncture without ultrasonic guide was safe and feasible for the breast cancer patients during adjuvant treatment and followup.

Examines the phenylalanine biosynthesis in Brevibacterium lactofermentum using Escherichia coli genes pheA, aroG and tyrB. Process of encoding 3-deoxy-D-arabino-heptulosonate-7-phosphate synthetase; Amplification of several genes by polymerase chain reaction; Activities of the enzyme in the host cells.